1. Field of the Invention
The present invention relates to an antenna device for a portable terminal. Particularly, the present invention relates to an antenna device for a portable terminal, which includes an antenna module disposed in an antenna jack of a terminal capable of TV service where the antenna module receives broadcasting signals depending on mounting/demounting of an external antenna.
2. Description of the Related Art
Recently, portable terminals have become multi-functional and downsized due to demands of consumers. Particularly, such multi-functional terminals provide voice communication service, radio service, and MP3 music download service via Internet. Additionally, it is possible to obtain digital information about various data and images with ease from portable terminals, Personal Digital Assistants (PDAs), computers and notebook computers.
Portable terminals generally include a Liquid Crystal Display (LCD) as data output device. Conventionally, a keypad including a plurality of keys is used for input of data.
In addition to the above, a portable terminal has an antenna device, located at a position with adequate space in its main body, for receiving signals transmitted from a counterpart terminal.
In some cases, a so-called fading phenomenon occurs in portable terminals during a transmission/reception process with a base station. The fading phenomenon is caused when the same signal is received through at least two different paths at different times, such that the received signals are distorted. In order to prevent the above-mentioned problem, a terminal is provided with a diversity antenna device, in addition to a standard antenna device, so that signals received from each antenna are combined to extract optimized signals and to ensure communication quality.
Additionally, it is possible to improve data communication speed of a terminal by using a diversity antenna device.
In one embodiment of a portable terminal, the above-mentioned diversity antenna device is disposed on the exterior of a terminal in the form of a set of a whip antenna and a helical antenna. The external antenna device is mounted with an internal antenna device.
Portable terminals with the above-described structure have spread quickly to consumers and are used widely. Also, there is a tendency to develop multi-functional portable terminals having various functions for satisfying the diverse needs of consumers, in addition to simple communication service. For example, besides voice communication, additional services for users include Video-On-Demand (VOD) service, image communication service, digital camera functions, Internet service, TV service, etc.
A portable terminal capable of TV service among the above additional services is referred to as a digital multimedia-broadcasting (DMB) terminal, which allows a user to watch TV programs through a display device, while also performing a mobile telecommunication function.
The portable terminal capable of TV service includes at least two Radio Frequency (RF) modules, because a frequency band necessary for transception of voices and data is different from a frequency band for broadcasting. Accordingly, the portable terminal capable of TV service is operated in a phone mode, waiting mode, and a broadcasting service mode, which is an image reception mode combined with a waiting mode.
As shown in FIGS. 1-3, the terminal has a diversity antenna device 3 including a broadcasting signal receiving module (not shown). An antenna jack 1a is disposed on a printed circuit board 4 embedded in the terminal 1 for interconnecting an external antenna 2 for exclusive use in broadcasting service with the broadcasting signal receiving module. The antenna jack 1a and connection jack 2a of the external antenna 2 for exclusive use in broadcasting service are joined with each other to receive TV broadcasting signals. Such received signals are applied to a broadcasting signal input module 5 disposed in the terminal.
As described above, signals received from the external antenna for exclusive use in the broadcasting service and from the diversity antenna device are combined to extract optimized signals, thereby preventing the so-called fading phenomenon and improving communication quality. As a result of the distance between the diversity antenna device and the external antenna (for exclusive use in the broadcasting service) increases, it is possible to obtain increasingly improved effects.
However, when a user watches TV using a conventional DMB terminal, it is necessary to use both the external antenna for exclusive use in the broadcasting service and the diversity antenna device. Therefore, it is necessary to provide a separate space in the terminal for mounting the diversity antenna, because a separate diversity antenna is mounted additionally to the terminal after connecting the antenna jack of the terminal with the external antenna for exclusive use of broadcasting service. As a result, it is inevitable that additional terminal space is required, thereby adversely affecting the ability to downsize of the terminal.
Additionally, because it is necessary to mount a separate diversity antenna to the terminal, the cost of antenna production increases and the time needed for assembly of the terminal increases due to the increased number of component elements.
Further, it is necessary for users to carry a conventional antenna for exclusive use of broadcasting service in their hands at all times in order to use it on demand. Therefore, there is a possibility of the loss of the antenna, resulting in degradation of its portability.